Propulsion system for an aircraft

ABSTRACT

A hybrid-electric propulsion system includes a turbomachine and an electrical system, the electrical system including an electric machine coupled to the turbomachine. A method for operating the propulsion system includes receiving, by one or more computing devices, a command to accelerate the turbomachine to provide a desired thrust output; receiving, by the one or more computing devices, data indicative of a temperature parameter approaching or exceeding an upper threshold; and providing, by the one or more computing devices, electrical power to the electric machine to add power to the turbomachine to provide, or assist with providing, the desired thrust output in response to receiving the command to accelerate the turbomachine and receiving the data indicative of the temperature parameter approaching or exceeding the upper threshold.

FIELD

The present subject matter relates generally to a hybrid-electricpropulsion system, and a method for operating the hybrid electricpropulsion system during hot ambient conditions and/or hot turbomachineconditions.

BACKGROUND

A conventional commercial aircraft generally includes a fuselage, a pairof wings, and a propulsion system that provides thrust. The propulsionsystem typically includes at least two aircraft engines, such asturbofan jet engines. Each turbofan jet engine is typically mounted to arespective one of the wings of the aircraft.

When operating during hot ambient conditions, a maximum amount of thrustthe propulsion system may produce is generally reduced as the hotambient air ingested by the turbofan jet engines causes the turbofan jetengines to reach a maximum internal temperature threshold more quickly.Accordingly, when an aircraft including the propulsion system isoperated in such hot ambient conditions, a maximum payload may belimited, a runway distance required for takeoff may be increased, etc.

Further, when the turbofan jet engines are operated at or near maximuminternal temperature thresholds, such as maximum exhaust gas temperaturethresholds, the turbofan jet engines may experience undesirable andpremature wear. Such may lead to a reduction in an overall time wing forthe turbofan jet engines, and an increase in necessary maintenance.

Accordingly, a propulsion system capable of operating during hot ambientconditions without significantly reducing the maximum amount of thrustavailable would be useful. Additionally, the propulsion system capableof maintaining the turbofan jet engines below the maximum internaltemperature thresholds would be particularly beneficial.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one exemplary aspect of the present disclosure, a method is providedfor operating a turbomachine of a hybrid-electric propulsion system ofan aircraft. The hybrid-electric propulsion system includes aturbomachine and an electrical system, the electrical system includingan electric machine coupled to the turbomachine. The method includesreceiving, by one or more computing devices, a command to accelerate theturbomachine to provide a desired thrust output; receiving, by the oneor more computing devices, data indicative of a temperature parameterapproaching or exceeding an upper threshold; and providing, by the oneor more computing devices, electrical power to the electric machine toadd power to the turbomachine to provide, or assist with providing, thedesired thrust output in response to receiving the command to acceleratethe turbomachine and receiving the data indicative of the temperatureparameter approaching or exceeding the upper threshold.

In certain exemplary aspects receiving, by one or more computingdevices, the command to accelerate the turbomachine to provide thedesired thrust output includes receiving, by one or more computingdevices, the command to accelerate the turbomachine during a pre-cruiseflight condition to provide the desired thrust output. For example, incertain exemplary aspects the pre-cruise flight condition is a takeoffflight condition or a climb flight condition.

In certain exemplary aspects receiving, by the one or more computingdevices, data indicative of the temperature parameter approaching orexceeding the upper threshold includes receiving, by the one or morecomputing devices, data indicative of an ambient temperature approachingor exceeding a hot day condition threshold for the turbomachine. Forexample, in certain exemplary aspects receiving, by the one or morecomputing devices, data indicative of the ambient temperatureapproaching or exceeding the hot day condition threshold includesreceiving, by the one or more computing devices, data from an ambienttemperature sensor. For example, in certain exemplary aspects receiving,by the one or more computing devices, data indicative of the ambienttemperature approaching or exceeding the hot day condition thresholdincludes receiving, by one or more computing devices, data from atemperature sensor within the turbomachine.

In certain exemplary aspects receiving, by the one or more computingdevices, data indicative of the temperature parameter approaching orexceeding the upper threshold includes determining, by the one or morecomputing devices, a delta value indicative of how far the temperatureparameter is above the upper threshold, and wherein providing, by theone or more computing devices, electrical power to the electric machineincludes modulating, by the one or more computing devices, the amount ofelectrical power provided to the electric machine based at least in parton the determined delta value.

In certain exemplary aspects the method further includes receiving, bythe one or more computing devices, data indicative of a turbomachinehealth parameter, and wherein providing, by the one or more computingdevices, electrical power to the electric machine includes modulating,by the one or more computing devices, the amount of electrical powerprovided to the electric machine based at least in part on the receiveddata indicative of the turbomachine health parameter.

In certain exemplary aspects the hybrid electric propulsion systemfurther includes an electric energy storage unit, and wherein providing,by the one or more computing devices, electrical power to the electricmachine includes providing, by the one or more computing devices,electrical power to the electric machine from the electric energystorage unit.

In certain exemplary aspects the hybrid electric propulsion systemfurther includes an electric energy storage unit, and the method furtherincludes receiving, by the one or more computing devices, dataindicative of a charge level of the electric energy storage unit; andterminating, by the one or more computing devices, the provision ofelectrical power to the electric machine at least in part in response toreceiving, by the one or more computing devices, the data indicative ofthe charge level of the electric energy storage unit.

In certain exemplary aspects the method further includes receiving, bythe one or more computing devices, data indicative of a temperature ofthe electric machine; and terminating, by the one or more computingdevices, the provision of electrical power to the electric machine atleast in part in response to receiving, by the one or more computingdevices, the data indicative of the temperature of the electric machine.

In certain exemplary aspects the method further includes receiving, bythe one or computing devices, data indicative of an operabilityparameter of the turbomachine; and terminating, by the one or morecomputing devices, the provision of electrical power to the electricmachine at least in part in response to the received data indicative ofthe operability parameter of the turbomachine. For example, in certainexemplary aspects the data indicative of the operability parameter isindicative of at least one of: a speed parameter of one or morecomponents of the turbomachine, a fuel flow to a combustion section ofthe turbomachine, an internal pressure of the turbomachine, or aninternal temperature of the turbomachine.

In certain exemplary aspects receiving, by the one or more computingdevices, data indicative of the temperature parameter approaching orexceeding the upper threshold includes receiving, by the one or morecomputing devices, data indicative of an exhaust gas temperatureparameter approaching or exceeding an upper exhaust gas temperatureparameter threshold. For example, in certain exemplary aspects theexhaust gas temperature parameter is indicative of an exhaust gastemperature, and wherein the upper exhaust gas temperature parameterthreshold is a predetermined exhaust gas temperature threshold. Forexample, in certain exemplary aspects the exhaust gas temperatureparameter is indicative of a rate of change of the exhaust gastemperature, and wherein the upper exhaust gas temperature parameterthreshold is a predetermined exhaust gas temperature rate of changethreshold.

In certain exemplary aspects providing, by the one or more computingdevices, electrical power to the electric machine includes providing atleast about fifteen horsepower of mechanical power to the turbomachine.

In an exemplary embodiment of the present disclosure, a hybrid-electricpropulsion system for an aircraft is provided. The hybrid-electricpropulsion system includes a propulsor; a turbomachine coupled to thepropulsor for driving the propulsor and generating thrust; an electricalsystem including an electric machine and an electric energy storage unitelectrically connectable to the electric machine, the electric machinecoupled to the turbomachine; and a controller. The controller isconfigured to receive a command to accelerate the turbomachine toprovide a desired thrust output and to received data indicative of atemperature parameter approaching or exceeding an upper threshold, thecontroller further configured to provide electrical power to theelectric machine to add power to the turbomachine to provide, or assistwith providing, the desired thrust output in response to receiving thecommand to accelerate the turbomachine and receiving the data indicativeof the temperature parameter approaching or exceeding the upperthreshold.

In certain exemplary embodiments the command to accelerate theturbomachine to provide the desired thrust output received by thecontroller is a command to accelerate the turbomachine during apre-cruise flight condition to provide the desired thrust output.

In certain exemplary embodiments the data indicative of the temperatureparameter approaching or exceeding the upper threshold includes dataindicative of an exhaust gas temperature parameter approaching orexceeding an upper exhaust gas temperature parameter threshold.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a top view of an aircraft according to various exemplaryembodiments of the present disclosure.

FIG. 2 is a schematic, cross-sectional view of a gas turbine enginemounted to the exemplary aircraft of FIG. 1.

FIG. 3 is a schematic, cross-sectional view of an electric fan assemblyin accordance with an exemplary embodiment of the present disclosure.

FIG. 4 is a schematic view of a propulsion system in accordance withanother exemplary embodiment of the present disclosure.

FIG. 5 is a flow diagram of a method for operating a hybrid electricpropulsion system of an aircraft in accordance with an exemplary aspectof the present disclosure.

FIG. 6 is a flow diagram of an exemplary aspect of the method of FIG. 5.

FIG. 7 is a computing system according to example aspects of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the invention.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

The terms “forward” and “aft” refer to relative positions within a gasturbine engine or vehicle, and refer to the normal operational attitudeof the gas turbine engine or vehicle. For example, with regard to a gasturbine engine, forward refers to a position closer to an engine inletand aft refers to a position closer to an engine nozzle or exhaust.

The terms “upstream” and “downstream” refer to the relative directionwith respect to a flow in a pathway. For example, with respect to afluid flow, “upstream” refers to the direction from which the fluidflows, and “downstream” refers to the direction to which the fluidflows. However, the terms “upstream” and “downstream” as used herein mayalso refer to a flow of electricity.

The singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

Approximating language, as used herein throughout the specification andclaims, is applied to modify any quantitative representation that couldpermissibly vary without resulting in a change in the basic function towhich it is related. Accordingly, a value modified by a term or terms,such as “about”, “approximately”, and “substantially”, are not to belimited to the precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value, or the precision of the methods or machines forconstructing or manufacturing the components and/or systems. Forexample, the approximating language may refer to being within a tenpercent margin.

Here and throughout the specification and claims, range limitations arecombined and interchanged, such ranges are identified and include allthe sub-ranges contained therein unless context or language indicatesotherwise. For example, all ranges disclosed herein are inclusive of theendpoints, and the endpoints are independently combinable with eachother.

The present disclosure is generally related to a hybrid electricpropulsion system having a turbomachine, a propulsor coupled to theturbomachine, and an electrical system. The electrical system includesan electric machine and an electric energy storage unit electricallyconnectable to the electric machine. Additionally, the electric machineis coupled to the turbomachine such that rotation of the turbomachinerotates the electric machine, and similarly, rotation of the electricmachine rotate one or more components of the turbomachine.

In certain operations of the hybrid electric propulsion system, thehybrid electric propulsion system is operable to assist with anacceleration of the turbomachine during hot ambient conditions and/orhot internal turbomachine conditions. For example, in certain exemplaryaspects, the hybrid electric propulsion system may receive a command toaccelerate the turbomachine to provide a desired thrust output, andfurther may receive data indicative of a temperature parameterapproaching or exceeding an upper threshold. Further, in response to thereceived command and the received data, the hybrid electric propulsionsystem may provide electrical power to the electric machine to and powerto the turbomachine to provide, or assist with providing, the desiredthrust output. For example, the power added by the electric machine tothe turbomachine may increase a rotational speed of a shaft or spoolwithin the turbomachine, which may, in turn, increase a rotational speedof the propulsor being driven by the turbomachine such that the hybridelectric propulsion system produces more thrust for the aircraft.

In certain exemplary aspects, the command to accelerate the turbomachinemay be received during a pre-cruise flight condition, such as a takeoffflight condition or a cruise flight condition. With such an exemplaryaspect, the temperature parameter may be an ambient temperatureparameter, such as in a situation in which the aircraft including thehybrid electric propulsion system is taking off during a hot daycondition.

Additionally, or alternatively, the command to accelerate theturbomachine may received during a flight condition, such as during acruise flight condition. Such a command may be for, e.g., a step climbprocedure, or other maneuver requiring the turbomachine to accelerate.With such an exemplary aspect, the temperature parameter may be aninternal temperature parameter for the turbomachine, such as an exhaustgas temperature parameter.

Regardless, the provision of electrical power to the electric machine toadd power to the turbomachine to provide, or assist with providing, thedesired thrust output may allow for the hybrid electric propulsionsystem to provide the desired thrust output despite, e.g., the hot dayconditions and/or the hot internal turbomachine conditions.

Referring now to the drawings, wherein identical numerals indicate thesame elements throughout the figures, FIG. 1 provides a top view of anexemplary aircraft 10 as may incorporate various embodiments of thepresent disclosure. As shown in FIG. 1, the aircraft 10 defines alongitudinal centerline 14 that extends therethrough, a lateraldirection L, a forward end 16, and an aft end 18. Moreover, the aircraft10 includes a fuselage 12, extending longitudinally from the forward end16 of the aircraft 10 to the aft end 18 of the aircraft 10, and anempennage 19 at the aft end of the aircraft 10. Additionally, theaircraft 10 includes a wing assembly including a first, port side wing20 and a second, starboard side wing 22. The first and second wings 20,22 each extend laterally outward with respect to the longitudinalcenterline 14. The first wing 20 and a portion of the fuselage 12together define a first side 24 of the aircraft 10, and the second wing22 and another portion of the fuselage 12 together define a second side26 of the aircraft 10. For the embodiment depicted, the first side 24 ofthe aircraft 10 is configured as the port side of the aircraft 10, andthe second side 26 of the aircraft 10 is configured as the starboardside of the aircraft 10.

Each of the wings 20, 22 for the exemplary embodiment depicted includesone or more leading edge flaps 28 and one or more trailing edge flaps30. The aircraft 10 further includes, or rather, the empennage 19 of theaircraft 10 includes, a vertical stabilizer 32 having a rudder flap (notshown) for yaw control, and a pair of horizontal stabilizers 34, eachhaving an elevator flap 36 for pitch control. The fuselage 12additionally includes an outer surface or skin 38. It should beappreciated however, that in other exemplary embodiments of the presentdisclosure, the aircraft 10 may additionally or alternatively includeany other suitable configuration. For example, in other embodiments, theaircraft 10 may include any other configuration of stabilizer.

Referring now also to FIGS. 2 and 3, the exemplary aircraft 10 of FIG. 1additionally includes a hybrid-electric propulsion system 50 having afirst propulsor assembly 52 and a second propulsor assembly 54. FIG. 2provides a schematic, cross-sectional view of the first propulsorassembly 52, and FIG. 3 provides a schematic, cross-sectional view ofthe second propulsor assembly 54. For the embodiment depicted, the firstpropulsor assembly 52 and second propulsor assembly 54 are eachconfigured in an underwing-mounted configuration. However, as will bediscussed below, one or both of the first and second propulsorassemblies 52, 54 may in other exemplary embodiments be mounted at anyother suitable location.

More particularly, referring generally to FIGS. 1 through 3, theexemplary hybrid-electric propulsion system 50 generally includes thefirst propulsor assembly 52 having a turbomachine and a prime propulsor(which, for the embodiment of FIG. 2 are configured together as a gasturbine engine, or rather as a turbofan engine 100), an electric machine56 (which for the embodiment depicted in FIG. 2 is an electricmotor/generator) drivingly coupled to the turbomachine, the secondpropulsor assembly 54 (which for the embodiment of FIG. 3 is configuredas an electric propulsor assembly 200), an electric energy storage unit55 (electrically connectable to the electric machine 56 and/or theelectric propulsor assembly 200), a controller 72, and a power bus 58.The electric propulsor assembly 200, the electric energy storage unit55, and the electric machine 56 are each electrically connectable to oneanother through one or more electric lines 60 of the power bus 58. Forexample, the power bus 58 may include various switches or other powerelectronics movable to selectively electrically connect the variouscomponents of the hybrid electric propulsion system 50. Additionally,the power bus 58 may further include power electronics, such asinverters, converters, rectifiers, etc., for conditioning or convertingelectrical power within the hybrid electric propulsion system 50.

As will be appreciated, the controller 72 may be configured todistribute electrical power between the various components of thehybrid-electric propulsion system 50. For example, the controller 72 maybe operable with the power bus 58 (including the one or more switches orother power electronics) to provide electrical power to, or drawelectrical power from, the various components, such as the electricmachine 56, to operate the hybrid electric propulsion system 50 betweenvarious operating modes and perform various functions. Such is depictedschematically as the electric lines 60 of the power bus 58 extendingthrough the controller 72, and will be discussed in greater detailbelow.

The controller 72 may be a stand-alone controller, dedicated to thehybrid-electric propulsion system 50, or alternatively, may beincorporated into one or more of a main system controller for theaircraft 10, a separate controller for the exemplary turbofan engine 100(such as a full authority digital engine control system for the turbofanengine 100, also referred to as a FADEC), etc. For example, thecontroller 72 may be configured in substantially the same manner as theexemplary computing system 500 described below with reference to FIG. 6(and may be configured to perform one or more of the functions of theexemplary method 300, described below).

Additionally, the electric energy storage unit 55 may be configured asone or more batteries, such as one or more lithium-ion batteries, oralternatively may be configured as any other suitable electrical energystorage devices. It will be appreciated that for the hybrid-electricpropulsion system 50 described herein, the electric energy storage unit55 is configured to store a relatively large amount of electrical power.For example, in certain exemplary embodiments, the electric energystorage unit may be configured to store at least about fifty kilowatthours of electrical power, such as at least about sixty-five kilowatthours of electrical power, such as at least about seventy-five kilowattshours of electrical power, and up to about one thousand kilowatt hoursof electrical power.

Referring now particularly to FIGS. 1 and 2, the first propulsorassembly 52 includes a gas turbine engine mounted, or configured to bemounted, to the first wing 20 of the aircraft 10. More specifically, forthe embodiment of FIG. 2, the gas turbine engine includes a turbomachine102 and a propulsor, the propulsor being a fan (referred to as “fan 104”with reference to FIG. 2). Accordingly, for the embodiment of FIG. 2,the gas turbine engine is configured as a turbofan engine 100.

The turbofan engine 100 defines an axial direction A1 (extendingparallel to a longitudinal centerline 101 provided for reference) and aradial direction R1. As stated, the turbofan engine 100 includes the fan104 and the turbomachine 102 disposed downstream from the fan 104.

The exemplary turbomachine 102 depicted generally includes asubstantially tubular outer casing 106 that defines an annular inlet108. The outer casing 106 encases, in serial flow relationship, acompressor section including a booster or low pressure (LP) compressor110 and a high pressure (HP) compressor 112; a combustion section 114; aturbine section including a first, high pressure (HP) turbine 116 and asecond, low pressure (LP) turbine 118; and a jet exhaust nozzle section120. The compressor section, combustion section 114, and turbine sectiontogether define at least in part a core air flowpath 121 through theturbomachine 102.

The exemplary turbomachine 102 of the turbofan engine 100 additionallyincludes one or more shafts rotatable with at least a portion of theturbine section and, for the embodiment depicted, at least a portion ofthe compressor section. More particularly, for the embodiment depicted,the turbofan engine 100 includes a high pressure (HP) shaft or spool122, which drivingly connects the HP turbine 116 to the HP compressor112. Additionally, the exemplary turbofan engine 100 includes a lowpressure (LP) shaft or spool 124, which drivingly connects the LPturbine 118 to the LP compressor 110.

Further, the exemplary fan 104 depicted is configured as a variablepitch fan having a plurality of fan blades 128 coupled to a disk 130 ina spaced apart manner. The fan blades 128 extend outwardly from disk 130generally along the radial direction R1. Each fan blade 128 is rotatablerelative to the disk 130 about a respective pitch axis P1 by virtue ofthe fan blades 128 being operatively coupled to a suitable actuationmember 132 configured to collectively vary the pitch of the fan blades128. The fan 104 is mechanically coupled to the LP shaft 124, such thatthe fan 104 is mechanically driven by the second, LP turbine 118. Moreparticularly, the fan 104, including the fan blades 128, disk 130, andactuation member 132, is mechanically coupled to the LP shaft 124through a power gearbox 134, and is rotatable about the longitudinalaxis 101 by the LP shaft 124 across the power gear box 134. The powergear box 134 includes a plurality of gears for stepping down therotational speed of the LP shaft 124 to a more efficient rotational fanspeed. Accordingly, the fan 104 is powered by an LP system (includingthe LP turbine 118) of the turbomachine 102.

Referring still to the exemplary embodiment of FIG. 2, the disk 130 iscovered by rotatable front hub 136 aerodynamically contoured to promotean airflow through the plurality of fan blades 128. Additionally, theturbofan engine 100 includes an annular fan casing or outer nacelle 138that circumferentially surrounds the fan 104 and/or at least a portionof the turbomachine 102. Accordingly, the exemplary turbofan engine 100depicted may be referred to as a “ducted” turbofan engine. Moreover, thenacelle 138 is supported relative to the turbomachine 102 by a pluralityof circumferentially-spaced outlet guide vanes 140. A downstream section142 of the nacelle 138 extends over an outer portion of the turbomachine102 so as to define a bypass airflow passage 144 therebetween.

Referring still to FIG. 2, the hybrid-electric propulsion system 50additionally includes an electric machine 56, which for the embodimentdepicted is configured as an electric motor/generator. The electricmachine 56 is, for the embodiment depicted, positioned within theturbomachine 102 of the turbofan engine 100, inward of the core airflowpath 121, and is coupled to/in mechanical communication with one ofthe shafts of the turbofan engine 100. More specifically, for theembodiment depicted, the electric machine is coupled to the second, LPturbine 118 through the LP shaft 124. The electric machine 56 may beconfigured to convert mechanical power of the LP shaft 124 to electricalpower (such that the LP shaft 124 drives the electric machine 56), oralternatively the electric machine 56 may be configured to convertelectrical power provided thereto into mechanical power for the LP shaft124 (such that the electric machine 56 drives, or assists with driving,the LP shaft 124).

It should be appreciated, however, that in other exemplary embodiments,the electric machine 56 may instead be positioned at any other suitablelocation within the turbomachine 102 or elsewhere. For example, theelectric machine 56 may be, in other embodiments, mounted coaxially withthe LP shaft 124 within the turbine section, or alternatively may beoffset from the LP shaft 124 and driven through a suitable gear train.Additionally, or alternatively, in other exemplary embodiments, theelectric machine 56 may instead be powered by the HP system, i.e., bythe HP turbine 116 through, e.g., the HP shaft 122, or by both the LPsystem (e.g., the LP shaft 124) and the HP system (e.g., the HP shaft122) via a dual drive system. Additionally, or alternatively, still, inother embodiments, the electric machine 56 may include a plurality ofelectric machines, e.g., with one being drivingly connected to the LPsystem (e.g., the LP shaft 124) and one being drivingly connected to theHP system (e.g., the HP shaft 122). Further, although the electricmachine 56 is described as an electric motor/generator, in otherexemplary embodiments, the electric machine 56 may be configured solelyas an electric generator.

Notably, in certain exemplary embodiments, the electric machine 56 maybe configured to generate at least about ten kilowatts of electricalpower when driven by the turbomachine 102, such as at least about fiftykilowatts of electrical power, such as at least about sixty-fivekilowatts of electrical power, such as at least about seventy-fivekilowatts of electrical power, such as at least about one hundredkilowatts of electrical power, such as up to five thousand kilowatts ofelectrical power. Additionally, or alternatively, the electric machine56 may be configured to provide, or otherwise add, at least aboutfifteen horsepower of mechanical power to the turbomachine 102 when theelectric machine 56 is provided electrical power from, e.g., theelectric energy storage unit 55. For example, in certain exemplaryembodiments, the electric machine 56 may be configured to provide atleast about fifty horsepower of mechanical power to the turbomachine102, such as at least about seventy-five horsepower, such as at leastabout one hundred horsepower, such as at least about one hundred andtwenty horsepower, such as up to about seven thousand horsepower.

Referring still to FIGS. 1 and 2, the turbofan engine 100 furtherincludes a controller 150 and a plurality of sensors (not shown). Thecontroller 150 may be a full authority digital engine control system,also referred to as a FADEC. The controller 150 of the turbofan engine100 may be configured to control operation of, e.g., the actuationmember 132, the fuel delivery system, etc. Additionally, referring backalso to FIG. 1, the controller 150 of the turbofan engine 100 isoperably connected to the controller 72 of the hybrid-electricpropulsion system 50. Moreover, as will be appreciated, the controller72 may further be operably connected to one or more of the firstpropulsor assembly 52 (including controller 150), the electric machine56, the second propulsor assembly 54, and the energy storage unit 55through a suitable wired or wireless communication system (depicted inphantom).

Moreover, although not depicted, in certain exemplary embodiments, theturbofan engine 100 may further include one or more sensors positionedto, and configured to, sense data indicative of one or more operationalparameters of the turbofan engine 100. For example, the turbofan engine100 may include one or more temperature sensors configured to sense atemperature within a core air flowpath 121 of the turbomachine 102. Forexample, such sensors may be configured to sense an exhaust gastemperature at an exit of the combustion section 114. Additionally, oralternatively, the turbofan engine 100 may include one or more pressuresensors to sense data indicative of a pressure within the core airflowpath 121 of the turbomachine 102, such as within a combustor withinthe combustion section 114 of the turbomachine 102. Further, in stillother exemplary embodiments, the turbofan engine 100 may also includeone or more speed sensors configured to sense data indicative of arotational speed of one or more components of the turbofan engine 100,such as one or more of the LP spool 124 or the HP spool 122.Additionally, in certain exemplary embodiments, the turbofan engine 100,the hybrid electric propulsion system as a whole, and/or an aircraftincorporating the hybrid electric propulsion system, may include one ormore ambient conditions sensors, such as one or more ambient temperaturesensors, positioned outside the core air flowpath 121 of theturbomachine 102 for sensing data indicative of an ambient condition,such as an ambient temperature. Accordingly, in at least certainexemplary embodiments, the hybrid electric propulsion system may receiveinformation regarding one or more ambient conditions from the aircraft.Notably, however, in other exemplary embodiments, ambient conditions maybe sensed within the core air flowpath 121 of the turbomachine 102,e.g., at the inlet 108.

It should further be appreciated that the exemplary turbofan engine 100depicted in FIG. 2 may, in other exemplary embodiments, have any othersuitable configuration. For example, in other exemplary embodiments, thefan 104 may not be a variable pitch fan, and further, in other exemplaryembodiments, the LP shaft 124 may be directly mechanically coupled tothe fan 104 (i.e., the turbofan engine 100 may not include the gearbox134). Further, it should be appreciated that in other exemplaryembodiments, the turbofan engine 100 may be configured as any othersuitable gas turbine engine. For example, in other embodiments, theturbofan engine 100 may instead be configured as a turboprop engine, anunducted turbofan engine, a turbojet engine, a turboshaft engine, etc.

Referring now particularly to FIGS. 1 and 3, as previously stated theexemplary hybrid-electric propulsion system 50 additionally includes thesecond propulsor assembly 54 mounted, for the embodiment depicted, tothe second wing 22 of the aircraft 10. Referring particularly to FIG. 3,the second propulsor assembly 54 is generally configured as an electricpropulsor assembly 200 including an electric motor 206 and apropulsor/fan 204. The electric propulsor assembly 200 defines an axialdirection A2 extending along a longitudinal centerline axis 202 thatextends therethrough for reference, as well as a radial direction R2.For the embodiment depicted, the fan 204 is rotatable about thecenterline axis 202 by the electric motor 206.

The fan 204 includes a plurality of fan blades 208 and a fan shaft 210.The plurality of fan blades 208 are attached to/rotatable with the fanshaft 210 and spaced generally along a circumferential direction of theelectric propulsor assembly 200 (not shown). In certain exemplaryembodiments, the plurality of fan blades 208 may be attached in a fixedmanner to the fan shaft 210, or alternatively, the plurality of fanblades 208 may be rotatable relative to the fan shaft 210, such as inthe embodiment depicted. For example, the plurality of fan blades 208each define a respective pitch axis P2, and for the embodiment depictedare attached to the fan shaft 210 such that a pitch of each of theplurality of fan blades 208 may be changed, e.g., in unison, by a pitchchange mechanism 211. Changing the pitch of the plurality of fan blades208 may increase an efficiency of the second propulsor assembly 54and/or may allow the second propulsor assembly 54 to achieve a desiredthrust profile. With such an exemplary embodiment, the fan 204 may bereferred to as a variable pitch fan.

Moreover, for the embodiment depicted, the electric propulsor assembly200 depicted additionally includes a fan casing or outer nacelle 212,attached to a core 214 of the electric propulsor assembly 200 throughone or more struts or outlet guide vanes 216. For the embodimentdepicted, the outer nacelle 212 substantially completely surrounds thefan 204, and particularly the plurality of fan blades 208. Accordingly,for the embodiment depicted, the electric propulsor assembly 200 may bereferred to as a ducted electric fan.

Referring still particularly to FIG. 3, the fan shaft 210 ismechanically coupled to the electric motor 206 within the core 214, suchthat the electric motor 206 drives the fan 204 through the fan shaft210. The fan shaft 210 is supported by one or more bearings 218, such asone or more roller bearings, ball bearings, or any other suitablebearings. Additionally, the electric motor 206 may be an inrunnerelectric motor (i.e., including a rotor positioned radially inward of astator), or alternatively may be an outrunner electric motor (i.e.,including a stator positioned radially inward of a rotor), oralternatively, still, may be an axial flux electric motor (i.e., withthe rotor neither outside the stator nor inside the stator, but ratheroffset from it along the axis of the electric motor).

As briefly noted above, the electrical power source (e.g., the electricmachine 56 or the electric energy storage unit 55) is electricallyconnected with the electric propulsor assembly 200 (i.e., the electricmotor 206) for providing electrical power to the electric propulsorassembly 200. More particularly, the electric motor 206 is in electricalcommunication with the electric machine 56 and/or the electric energystorage unit 55 through the electrical power bus 58, and moreparticularly through the one or more electrical cables or lines 60extending therebetween.

It should be appreciated, however, that in other exemplary embodimentsthe exemplary hybrid-electric propulsion system 50 may have any othersuitable configuration, and further, may be integrated into an aircraft10 in any other suitable manner. For example, in other exemplaryembodiments, the electric propulsor assembly 200 of the hybrid electricpropulsion system 50 may instead be configured as a plurality ofelectric propulsor assemblies 200 and/or the hybrid electric propulsionsystem 50 may further include a plurality of gas turbine engines (suchas turbofan engine 100) and electric machines 56.

Further, in other exemplary embodiments, the electric propulsorassembly(ies) 200 and/or gas turbine engine(s) and electric machine(s)56 may be mounted to the aircraft 10 at any other suitable location inany other suitable manner (including, e.g., tail mountedconfigurations). For example, in certain exemplary embodiments, theelectric propulsor assembly may be configured to ingest boundary layerair and reenergize such boundary layer air to provide a propulsivebenefit for the aircraft (the propulsive benefit may be thrust, or maysimply be an increase in overall net thrust for the aircraft by reducinga drag on the aircraft).

Moreover, in still other exemplary embodiments, the exemplary hybridelectric propulsion system 50 may have still other configurations. Forexample, in other exemplary embodiments, the hybrid electric propulsionsystem 50 may not include a “pure” electric propulsor assembly. Forexample, referring now briefly to FIG. 4, a schematic diagram of ahybrid-electric propulsion system 50 in accordance with yet anotherexemplary embodiment of the present disclosure is provided. Theexemplary hybrid electric propulsion system 50 depicted in FIG. 4 may beconfigured in a similar manner as one or more the exemplary hybridelectric propulsion systems 50 described above with reference to FIGS. 1through 3.

For example, the exemplary hybrid-electric propulsion system 50 of FIG.4 generally includes a first propulsor assembly 52 and a secondpropulsor assembly 54. The first propulsor assembly generally includes afirst turbomachine 102A and a first propulsor 104A, and similarly, thesecond propulsor assembly 54 generally includes a second turbomachine102B and a second propulsor 104B. Each of the first and secondturbomachines 102A, 102B generally includes a low pressure system havinga low pressure compressor 110 drivingly coupled to a low pressureturbine 118 through a low pressure shaft 124, as well as a high pressuresystem having a high pressure compressor 112 drivingly coupled to a highpressure turbine 116 through a high pressure shaft 122. Additionally,the first propulsor 104A is drivingly coupled to the low pressure systemof the first turbomachine 102A and the second propulsor 104B isdrivingly coupled to the low pressure system of the second turbomachine102B. In certain exemplary embodiments, the first propulsor 104A andfirst turbomachine 102A may be configured as a first turbofan engine andsimilarly, the second propulsor 104B and second turbomachine 102B may beconfigured as a second turbofan engine (e.g., similar to the exemplaryturbofan engine 100 of FIG. 2). Alternatively, however, these componentsmay instead be configured as parts of a turboprop engine or any othersuitable turbomachine-driven propulsion device. Further, in certainexemplary embodiments, the first propulsor assembly 52 may be mounted toa first wing of an aircraft and the second propulsor assembly 54 may bemounted to a second wing of the aircraft (similar, e.g., to theexemplary embodiment of FIG. 1). Of course, in other exemplaryembodiments, any other suitable configuration may be provided (e.g.,both may be mounted to the same wing, one or both may be mounted to atail of the aircraft, etc.).

Moreover, the hybrid electric propulsion system 50 of FIG. 4additionally includes an electrical system. The electrical systemincludes a first electric machine 56A, a second electric machine 56B,and an electric energy storage unit 55 electrically connectable to thefirst electric machine 56A and second electric machine 56B. The firstelectric machine 56A is additionally coupled to the first turbomachine102A. More specifically, for the embodiment depicted, the first electricmachine 56A is coupled to the high pressure system of the firstturbomachine 102A, and more specifically still, is coupled to thehigh-pressure spool 122 of the first turbomachine 102A. In such amanner, the first electric machine 56A may extract power from the highpressure system of the first turbomachine 102A and/or provide power tothe high-pressure system of the first turbomachine 102A.

Further, it will be appreciated that for the embodiment depicted, thesecond propulsor assembly 54 is not configured as a pure electricpropulsor assembly. Instead, the second propulsor assembly 54 isconfigured as part of a hybrid electric propulsor. More particularly,the second electric machine 56B is coupled to the second propulsor 104B,and is further coupled to the low pressure system of the secondturbomachine 102B. In such a manner, the second electric machine 56B mayextract power from the low pressure system of the second turbomachine102B and/or provide power to the low pressure system of the firstturbomachine 102A. More particularly, in certain exemplary aspects, thesecond electric machine 56 may drive, or assist with driving the secondpropulsor 104B.

As is also depicted in FIG. 4, the exemplary hybrid electric propulsionsystem 50 further includes a controller 72 and a power bus 58. The firstelectric machine 56A, the second electric machine 56B, and the electricenergy storage unit 55 are each electrically connectable to one anotherthrough one or more electric lines 60 of the power bus 58. For example,the power bus 58 may include various switches or other power electronicsmovable to selectively electrically connect the various components ofthe hybrid electric propulsion system 50, and optionally to convert orcondition such electrical power transferred therethrough. Accordingly,in certain operations, the first electric machine 56A may provideelectrical power to the second electric machine 56B, or vice versa.Additionally, or alternatively, the first electric machine 56A and/orthe second electric machine 56B may provide electrical power to theelectric energy storage unit 55, or the electric energy storage unit 55may provide electrical power to the first electric machine 56A and/orthe second electric machine 56B.

Furthermore, it should be appreciated that in still other exemplaryembodiments, the exemplary hybrid electric propulsion system 50 may haveother suitable configurations. For example, although the exemplaryembodiment of FIG. 4 includes a first electric machine 56A coupled tothe high-pressure system of the first turbomachine 102A and the secondelectric machine 56B coupled to the low pressure system of the secondturbomachine 102B, in other exemplary embodiments, each of the electricmachines 56A, 56B may be coupled to the low pressure system, oralternatively may be coupled to the high-pressure system. Alternatively,in other exemplary embodiments the electrical system may further includean additional electric machine coupled to the low pressure system of thefirst turbomachine 102A and/or an additional electric machine coupled tothe high-pressure system of the second turbomachine 102B.

Referring now to FIG. 5, a flow diagram of a method 300 for operating ahybrid electric propulsion system of an aircraft is provided. The method300 may generally be operable with one or more of the exemplary hybridelectric propulsion systems described above with reference to FIGS. 1through 4. For example, the hybrid electric propulsion system maygenerally include a turbomachine and an electrical system, with theelectrical system including an electric machine coupled to theturbomachine and an electric energy storage unit. The electric energystorage unit may be electrically connectable to the electric machine.Notably, in certain exemplary aspects, the hybrid electric propulsionsystem may further include a propulsor coupled to the turbomachine.

As is depicted, the method 300 includes at (302) receiving, by one ormore computing devices, a command to accelerate the turbomachine toprovide a desired thrust output. For the exemplary aspect depicted,receiving, by the one or more computing devices, the command toaccelerate the turbomachine to provide the desired thrust output at(302) includes at (304) receiving, by the one or more computing devices,the command to accelerate the turbomachine during a pre-cruise flightcondition to provide the desired thrust output. The pre-cruise flightcondition may be, for example, a takeoff flight condition or a climbflight condition. Alternatively, however, in other exemplary aspects,the command received at (302) may be received during any other suitableflight condition requiring an acceleration of the turbomachine. Forexample, the command received at (302) may be received during a cruiseoperating mode in order to perform, e.g., a step climb maneuver.Regardless, the command to accelerate the turbomachine may be receivedfrom, e.g., a flight crew member of the aircraft through one or moreinput devices of the aircraft, or alternatively may be received as partof a control algorithm executed by a controller of the hybrid electricpropulsion system and/or aircraft.

The method 300 further includes at (306) receiving, by the one or morecomputing devices, data indicative of a temperature parameterapproaching or exceeding an upper threshold. Notably, as used herein,the term “approaching or exceeding” refers to a parameter value beingwithin a predetermined range of a threshold, or being above thethreshold. In certain exemplary aspects, such as the exemplary aspectdepicted, receiving, by the one or more computing devices, dataindicative of the temperature parameter approaching or exceeding theupper threshold at (306) includes at (308) receiving, by the one or morecomputing devices, data indicative of an ambient temperature approachingor exceeding a hot day condition threshold for the turbomachine. The hotday condition threshold may be a temperature threshold above which theturbomachine is limited in an amount of effective output power it mayproduce by virtue of the ingested ambient air being too hot. Forexample, as will be appreciated, as the turbomachine combusts fuel, anamount of heat is added to the airflow through the engine. As a startingtemperature (i.e., an ambient temperature) of the airflow provided tothe turbomachine increases, less heat, or energy, may be added theretobefore thermal limits within the turbomachine are reached. In such amanner, the relatively high ambient temperature may limit theturbomachine's performance. In certain exemplary aspects, the hot daycondition threshold may be approximately eighty-five degrees Fahrenheit.However, for other hybrid electric propulsion systems, or rather, forother turbomachines, the hot day temperature threshold may have anyother value.

In certain exemplary aspects, the data indicative of the ambienttemperature may be received from, e.g., an ambient temperature sensorlocated outside of the turbomachine (e.g., on the aircraft), oralternatively, an internal temperature sensor located within theturbomachine (e.g., at an inlet to the turbomachine). Accordingly, as isdepicted in phantom, in certain exemplary aspects, receiving, by the oneor more computing devices, data indicative of the ambient temperatureapproaching or exceeding the hot day condition threshold may include at(310) receiving, by the one or more computing devices, data from anambient temperature sensor, or alternatively, at (312) receiving, by theone or more computing devices, data from a temperature sensor within theturbomachine.

However, in other exemplary aspects of the present disclosure, thetemperature parameter may be any other suitable temperature parameter.For example, as is also shown in the exemplary aspect of the method 300depicted in FIG. 5, in at least certain exemplary aspects, receiving, bythe one or more computing devices, data indicative of the temperatureparameter approaching or exceeding the upper threshold at (306) includesat (314) receiving, by the one or more computing devices, dataindicative of an exhaust gas temperature parameter approaching orexceeding an upper exhaust gas temperature parameter threshold. Forexample, in at least certain exemplary aspects, the exhaust gastemperature parameter may be indicative of an exhaust gas temperaturewithin the turbomachine. In such an exemplary aspect, the upper exhaustgas temperature parameter threshold may be a predetermined exhaust gastemperature threshold. Additionally, or alternatively, in certainexemplary aspects, the exhaust gas temperature parameter may beindicative of a rate of change of the exhaust gas temperature within theturbomachine. With such an exemplary aspect, the upper exhaust gastemperature parameter threshold may be a predetermined exhaust gastemperature rate of change threshold. As will be appreciated, operatingthe turbomachine at or near a thermal limit of the turbomachine, e.g.,as may be determined by the exhaust gas temperature parameter, may causepremature wear within the engine by thermally stressing variouscomponents within the engine.

Moreover, the exemplary aspect depicted further includes at (316)providing, by the one or more computing devices, electrical power to theelectric machine to add power to the turbomachine to provide, or assistwith providing, the desired thrust output in response to receiving thecommand to accelerate the turbomachine at (302) and receiving the dataindicative of the temperature parameter approaching or exceeding theupper threshold at (306). For example, for the exemplary aspect depictedproviding, by the one or more computing devices, electrical power to theelectric machine at (316) includes at (318) providing, by the one ormore computing devices, electrical power to the electric machine fromthe electric energy storage unit. Additionally, it will be appreciatedthat in at least certain exemplary aspects, providing, by the one ormore computing devices, electrical power to the electric machine at(316) may include providing at least about fifteen horsepower ofmechanical power to the turbomachine. It will be appreciated, however,that in other exemplary aspects of the method 300, providing, by the oneor more computing devices, electrical power to the electric machine at(316) may additionally, or alternatively, include providing electricalpower to the electric machine from a second electric machine coupled toa second turbomachine (see, e.g., embodiment of FIG. 4).

By providing the electrical power to the electric machine in accordancewith one or more exemplary aspects of the present disclosure, the hybridelectric propulsion system may provide the desired thrust output despitethe relatively high ambient temperatures and/or relatively hightemperatures internal to the turbomachine. Such may therefore providefor more versatile and efficient hybrid electric propulsion system

Referring still to the exemplary method 300 depicted in FIG. 5, it willfurther be appreciated that in at least certain exemplary aspects,providing, by the one or more computing devices, electrical power to theelectric machine at (316) may include providing a substantially constantamount of electrical power for an amount of time. However, for theexemplary aspect of the method 300 depicted, providing, by the one ormore computing devices, electrical power to the electric machine at(316) includes at (320) modulating, by the one or more computingdevices, the amount of electrical power provided to the electricmachine.

More specifically, for the exemplary aspect depicted, it will beappreciated that receiving, by the one or more computing devices, dataindicative of the temperature parameter approaching or exceeding theupper threshold at (306) further includes at (322) determining, by theone or more computing devices, a delta value indicative of how far thetemperature parameter is above the upper threshold. For example, incertain exemplary aspects, determining the delta value at (322) mayinclude determining a delta value indicative of how far the ambienttemperature is above the hot day condition threshold, or alternativelyhow far the exhaust gas temperature parameter is above the upper exhaustgas temperature parameter threshold. Regardless, with such an exemplaryaspect, modulating, by the one or more computing devices, the amount ofelectrical power provided to the electric machine at (320) includes at(324) modulating, by the one or more computing devices, the amount ofelectrical power provided to the electric machine based at least in parton the delta value determined at (322). For example, the higher thedelta value that is determined, the more electrical power the method 300may provide to the electric machine.

It will be appreciated, however, that in other exemplary aspects, themethod 300 may modulate the amount of electrical power at (320) based onany other suitable parameter. For example, as is also depicted in FIG.5, the method 300 further includes at (326) receiving, by the one ormore computing devices, data indicative of a turbomachine healthparameter. The turbomachine health parameter may be any parameterindicative of an amount of degradation the turbomachine has undergone.With such an exemplary aspect, modulating, by the one or more computingdevices, the amount of electrical power provided to the electric machineat (320) includes at (328) modulating, by the one or more computingdevices, the amount of electrical power provided to the electric machinebased at least in part on the received data indicative of theturbomachine health parameter. For example, the more the turbomachinehas degraded, the more electrical power the method 300 may provide tothe electric machine, e.g., to compensate for such degradation.

By operating in accordance with one or more these exemplary aspects, themethod 300 may provide a sufficient amount of electrical power to theelectric machine to assist the turbomachine in providing the desiredthrust output, while still conserving electrical power.

Referring now also to FIG. 6, providing a close-up flow diagram of anexemplary aspect of the exemplary method 300 described above, it will beappreciated that the method 300 further includes at (330) terminating,by the one or more computing devices, the provision of electrical powerto the electric machine (i.e., terminate the providing of electricalpower to the electric machine at (316)). As will be appreciated,terminating, by the one or more computing devices, the provision ofelectrical power to the electric machine at (330) may be in response toa number of various parameters.

For example, for the exemplary aspect depicted, the method 300 furtherincludes at (332) receiving, by the one or more computing devices, dataindicative of a charge level of the electric energy storage unit. Thedata indicative of the charge level of the electric energy storage unitmay be data indicative of the charge level of the electric energystorage unit being below a lower threshold or approaching a lowerthreshold. For example, the data indicative of the charge level of theelectric energy storage unit may be data indicative of the charge levelbeing below a predetermined lower threshold for performing certainoperations, such as an engine start or restart, or some other minimumoperating threshold for the electric energy storage unit. With such anexemplary aspect, terminating, by the one or more computing devices, theprovision of electrical power to the electric machine at (330) includesat (334) terminating, by the one or more computing devices, theprovision of electrical power to the electric machine at least in partin response to receiving, by the one or more computing devices, the dataindicative of the charge level of the electric energy storage unit at(332).

Moreover, the exemplary aspect of the method 300 depicted in FIG. 6further includes at (336) receiving, by the one or more computingdevices, data indicative of a temperature of the electric machine. Thedata indicative of the temperature of the electric machine received at(336) may indicate that the electric machine is above a desiredoperating temperature threshold. For example, the electric machine maybe more susceptible to damage when operated above the desired operatingtemperature threshold. Accordingly, for the exemplary aspect depicted,in order to minimize a risk of damaging the electric machine,terminating, by the one or more computing devices, the provision ofelectrical power to the electric machine at (330) includes at (338)terminating, by the one or more computing devices, the provision ofelectrical power to the electric machine at least in part in response toreceiving, by the one or more computing devices, the data indicative ofthe temperature of the electric machine at (336).

Furthermore, the exemplary aspect of the method 300 depicted in FIG. 6additionally includes at (340) receiving, by the one or more computingdevices, data indicative of an operability parameter of theturbomachine. The data indicative of the operability parameter theturbomachine received at (340) may be indicative of a speed parameter ofone or more components the turbomachine, a fuel flow to a combustionsection of the turbomachine, an internal pressure of the turbomachine,and/or an internal temperature of the turbomachine. For example, thespeed parameter of the one or more components of the turbomachine may bea rotational speed of one or more spools within the turbomachine, anacceleration of one or more spools within the turbomachine, orcombination thereof. The data indicative of the operability parameterreceived at (340) may indicate that the turbomachine is operating at adesired operability, such as indicating that the hybrid electricpropulsion system is providing the desired thrust output, that theturbomachine is accelerating at a desired rate or otherwise operating adesired rotational speed, etc. Accordingly, for the exemplary aspect,terminating, by the one or more computing devices, the provision ofelectrical power to the electric machine at (330) includes at (342)terminating, by the one or more computing devices the provision ofelectrical power to the electric machine at least in part in response tothe received data indicative of the operability parameter of theturbomachine at (340). In such a manner, the method 300 may terminateprovision of electric power to the electric machine once the operabilityparameter indicates supplemental power is no longer necessary, or saidanother way, the method 300 may provide electric power to the electricmachine only for so long as supplemental power is necessary.

Operating a hybrid electric propulsion system in accordance with one ormore exemplary aspects of the method 300 of FIG. 6 may allow theelectric machine of the hybrid electric propulsion system to assist withproviding the desired thrust output while conserving electrical power,preventing damage to the electric machine, etc.

Referring now to FIG. 7, an example computing system 500 according toexample embodiments of the present disclosure is depicted. The computingsystem 500 can be used, for example, as a controller 72 in a hybridelectric propulsion system 50. The computing system 500 can include oneor more computing device(s) 510. The computing device(s) 510 can includeone or more processor(s) 510A and one or more memory device(s) 510B. Theone or more processor(s) 510A can include any suitable processingdevice, such as a microprocessor, microcontroller, integrated circuit,logic device, and/or other suitable processing device. The one or morememory device(s) 510B can include one or more computer-readable media,including, but not limited to, non-transitory computer-readable media,RAM, ROM, hard drives, flash drives, and/or other memory devices.

The one or more memory device(s) 510B can store information accessibleby the one or more processor(s) 510A, including computer-readableinstructions 510C that can be executed by the one or more processor(s)510A. The instructions 510C can be any set of instructions that whenexecuted by the one or more processor(s) 510A, cause the one or moreprocessor(s) 510A to perform operations. In some embodiments, theinstructions 510C can be executed by the one or more processor(s) 510Ato cause the one or more processor(s) 510A to perform operations, suchas any of the operations and functions for which the computing system500 and/or the computing device(s) 510 are configured, the operationsfor operating a turbomachine (e.g, method 300), as described herein,and/or any other operations or functions of the one or more computingdevice(s) 510. Accordingly, the method 300 may be computer-implementedmethods. The instructions 510C can be software written in any suitableprogramming language or can be implemented in hardware. Additionally,and/or alternatively, the instructions 510C can be executed in logicallyand/or virtually separate threads on processor(s) 510A. The memorydevice(s) 510B can further store data 510D that can be accessed by theprocessor(s) 510A. For example, the data 510D can include dataindicative of power flows, data indicative of power demands of variousloads in a hybrid electric propulsion system, data indicative ofoperational parameters of the hybrid electric propulsion system,including of a turbomachine of the hybrid electric propulsion system.

The computing device(s) 510 can also include a network interface 510Eused to communicate, for example, with the other components of system500 (e.g., via a network). The network interface 510E can include anysuitable components for interfacing with one or more network(s),including for example, transmitters, receivers, ports, controllers,antennas, and/or other suitable components. One or more external displaydevices (not depicted) can be configured to receive one or more commandsfrom the computing device(s) 510.

The technology discussed herein makes reference to computer-basedsystems and actions taken by and information sent to and fromcomputer-based systems. One of ordinary skill in the art will recognizethat the inherent flexibility of computer-based systems allows for agreat variety of possible configurations, combinations, and divisions oftasks and functionality between and among components. For instance,processes discussed herein can be implemented using a single computingdevice or multiple computing devices working in combination. Databases,memory, instructions, and applications can be implemented on a singlesystem or distributed across multiple systems. Distributed componentscan operate sequentially or in parallel.

Although specific features of various embodiments may be shown in somedrawings and not in others, this is for convenience only. In accordancewith the principles of the present disclosure, any feature of a drawingmay be referenced and/or claimed in combination with any feature of anyother drawing.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A method for operating a turbomachine of ahybrid-electric propulsion system of an aircraft, the hybrid-electricpropulsion system comprising a turbomachine and an electrical system,the electrical system comprising an electric machine coupled to theturbomachine, the method comprising: receiving, by one or more computingdevices, a command to accelerate the turbomachine to provide a desiredthrust output; receiving, by the one or more computing devices, dataindicative of a temperature parameter approaching or exceeding an upperthreshold; and providing, by the one or more computing devices,electrical power to the electric machine to add power to theturbomachine to provide, or assist with providing, the desired thrustoutput in response to receiving the command to accelerate theturbomachine and receiving the data indicative of the temperatureparameter approaching or exceeding the upper threshold.
 2. The method ofclaim 1, wherein receiving, by one or more computing devices, thecommand to accelerate the turbomachine to provide the desired thrustoutput comprises receiving, by one or more computing devices, thecommand to accelerate the turbomachine during a pre-cruise flightcondition to provide the desired thrust output.
 3. The method of claim2, wherein the pre-cruise flight condition is a takeoff flight conditionor a climb flight condition.
 4. The method of claim 1, whereinreceiving, by the one or more computing devices, data indicative of thetemperature parameter approaching or exceeding the upper thresholdcomprises receiving, by the one or more computing devices, dataindicative of an ambient temperature approaching or exceeding a hot daycondition threshold for the turbomachine.
 5. The method of claim 4,wherein receiving, by the one or more computing devices, data indicativeof the ambient temperature approaching or exceeding the hot daycondition threshold comprises receiving, by the one or more computingdevices, data from an ambient temperature sensor.
 6. The method of claim4, wherein receiving, by the one or more computing devices, dataindicative of the ambient temperature approaching or exceeding the hotday condition threshold comprises receiving, by one or more computingdevices, data from a temperature sensor within the turbomachine.
 7. Themethod of claim 1, wherein receiving, by the one or more computingdevices, data indicative of the temperature parameter approaching orexceeding the upper threshold comprises determining, by the one or morecomputing devices, a delta value indicative of how far the temperatureparameter is above the upper threshold, and wherein providing, by theone or more computing devices, electrical power to the electric machinecomprises modulating, by the one or more computing devices, the amountof electrical power provided to the electric machine based at least inpart on the determined delta value.
 8. The method of claim 1, furthercomprising: receiving, by the one or more computing devices, dataindicative of a turbomachine health parameter, and wherein providing, bythe one or more computing devices, electrical power to the electricmachine comprises modulating, by the one or more computing devices, theamount of electrical power provided to the electric machine based atleast in part on the received data indicative of the turbomachine healthparameter.
 9. The method of claim 1, wherein the hybrid electricpropulsion system further comprises an electric energy storage unit, andwherein providing, by the one or more computing devices, electricalpower to the electric machine comprises providing, by the one or morecomputing devices, electrical power to the electric machine from theelectric energy storage unit.
 10. The method of claim 1, wherein thehybrid electric propulsion system further comprises an electric energystorage unit, and wherein the method further comprises: receiving, bythe one or more computing devices, data indicative of a charge level ofthe electric energy storage unit; and terminating, by the one or morecomputing devices, the provision of electrical power to the electricmachine at least in part in response to receiving, by the one or morecomputing devices, the data indicative of the charge level of theelectric energy storage unit.
 11. The method of claim 1, furthercomprising: receiving, by the one or more computing devices, dataindicative of a temperature of the electric machine; and terminating, bythe one or more computing devices, the provision of electrical power tothe electric machine at least in part in response to receiving, by theone or more computing devices, the data indicative of the temperature ofthe electric machine.
 12. The method of claim 1, further comprising:receiving, by the one or computing devices, data indicative of anoperability parameter of the turbomachine; and terminating, by the oneor more computing devices, the provision of electrical power to theelectric machine at least in part in response to the received dataindicative of the operability parameter of the turbomachine.
 13. Themethod of claim 12, wherein the data indicative of the operabilityparameter is indicative of at least one of: a speed parameter of one ormore components of the turbomachine, a fuel flow to a combustion sectionof the turbomachine, an internal pressure of the turbomachine, or aninternal temperature of the turbomachine.
 14. The method of claim 1,wherein receiving, by the one or more computing devices, data indicativeof the temperature parameter approaching or exceeding the upperthreshold comprises receiving, by the one or more computing devices,data indicative of an exhaust gas temperature parameter approaching orexceeding an upper exhaust gas temperature parameter threshold.
 15. Themethod of claim 14, wherein the exhaust gas temperature parameter isindicative of an exhaust gas temperature, and wherein the upper exhaustgas temperature parameter threshold is a predetermined exhaust gastemperature threshold.
 16. The method of claim 14, wherein the exhaustgas temperature parameter is indicative of a rate of change of theexhaust gas temperature, and wherein the upper exhaust gas temperatureparameter threshold is a predetermined exhaust gas temperature rate ofchange threshold.
 17. The method of claim 1, wherein providing, by theone or more computing devices, electrical power to the electric machineincludes providing at least about fifteen horsepower of mechanical powerto the turbomachine.
 18. A hybrid-electric propulsion system for anaircraft comprising: a propulsor; a turbomachine coupled to thepropulsor for driving the propulsor and generating thrust; an electricalsystem comprising an electric machine and an electric energy storageunit electrically connectable to the electric machine, the electricmachine coupled to the turbomachine; and a controller configured toreceive a command to accelerate the turbomachine to provide a desiredthrust output and to received data indicative of a temperature parameterapproaching or exceeding an upper threshold, the controller furtherconfigured to provide electrical power to the electric machine to addpower to the turbomachine to provide, or assist with providing, thedesired thrust output in response to receiving the command to acceleratethe turbomachine and receiving the data indicative of the temperatureparameter approaching or exceeding the upper threshold.
 19. Thehybrid-electric propulsion system of claim 18, wherein the command toaccelerate the turbomachine to provide the desired thrust outputreceived by the controller is a command to accelerate the turbomachineduring a pre-cruise flight condition to provide the desired thrustoutput.
 20. The hybrid-electric propulsion system of claim 18, whereinthe data indicative of the temperature parameter approaching orexceeding the upper threshold comprises data indicative of an exhaustgas temperature parameter approaching or exceeding an upper exhaust gastemperature parameter threshold.